This invention relates to manually actuated pump sprayers for dispensing a liquid in a jet or atomization mode from spray containers, or to pressurized gas containers and, more particularly, to a feed structure that, as the result of surface tension forces, allows liquid to be expelled while preventing the flow of gas regardless of the orientation of the container.
There are two basic spray dispensing containers: the first one employs a hand pump to draw a liquid into a feed tube in liquid communication with the hand pump and then spray the liquid out of an exit orifice; the second one employs a pressurized gas to force the liquid contents into the feed tube to be dispensed when a spray valve is actuated.
The use of hand pump spray bottles or pressurized cans to dispense a variety of substances such as glass cleaners, paints, perfumes, and other personal care products, is widespread. Most of such containers have a single feed tube with an open end that extends into the liquid contents if the container is held in an upright position. In the upright position, the liquid can reach the hand pump and be dispensed or forced out the spray valve in a pressurized container. However, if the container is inverted, the entrance to the feed tube is exposed to gas, and then only gas can be expelled from the container.
There are numerous patents which relate to the design of novel feed structures and hand pumps that can operate in either the fully upright position or the fully inverted position. The teachings of many of these patents are based on using check valves that are dependent on the force of gravity to open or close the valves. Typical patents of this type are U.S. Pat. No. 4,775,079 and U.S. Pat. No. 3,733,013 where, in addition to the conventional opening at the distal end of the feed tube, a second opening is located near the hand pump or spray valve entrance in the case of a pressurized can. This second entrance is opened or closed by a ball or weight device that is seated or unseated by the force of gravity. When the container is inverted partially so that the open end of the feed tube is not in contact with the liquid and even if the second opening is immersed in liquid, the system will not operate reliably. This occurs because the component of the force of gravity is insufficient to move the ball or weight to uncover the second opening which is in contact with the liquid. The result is that the system will expel gas/air from within the container rather than liquid. Alternatively, after inverted operation, when the container is oriented approximately upright so that the distal end of the feed tube is immersed in liquid and the second opening is exposed to air, the component of gravity is insufficient to reseal the ball or weight and air is ingested into the hand pump or spray valve instead of liquid. Because of this difficulty of obtaining an acceptable gas seal with a ball or weight which is held in position by gravity, none of these types of patents provides for reliable operation at orientations between the nearly fully upright and the nearly fully inverted positions. Only at orientations of nearly upright or nearly inverted positions will the force of gravity be sufficient to seat or unset the ball or slug in a reliable fashion. A further disadvantage of this type of device is the appreciable cost of the check valve compared to the cost of the conventional hand pump or spray valve.
Another group of patents describes feed tube configurations that will pass some types of fluids but not others. These concepts do not require check valves to operate. Typical of these is U.S. Pat. No. 4,418,846 that describes two immiscible liquids, one that is a lipophilic phase and the other is a non-lipophilic phase. U.S. Pat. No. 4,398,654 describes a similar feed tube with an open end through which can pass an aqueous liquid and a tubular structure through which a non-aqueous liquid can flow. These structures operate satisfactorily only if the container is in an upright position and are mentioned here merely to show a method for allowing one type of fluid to pass and to prevent another type of fluid from passing through an opening.
There are several patents for rocket propellant feed systems that operate in zero or near zero gravity fields. U.S. Pat. No. 4,272,257 by the present inventor is typical of this type of structure. Although these patents employ surface tension devices to prevent gas from leaving the container as does this patent, none of them relates to spray bottles that operate in a gravity field and they all require multiple, complex, expensive porous entrance devices.
The aforementioned parent application Ser. No. 08/866,037 discloses a hand-pump for a spray bottle that, in addition to the conventional opening at the distal end of the feed tube, has only a single second opening. The second opening has flow passages that, when wetted, provide surface tension forces that restrict the entrance of air to the hand pump but pass liquid freely. The result is that only liquid is dispensed either in the upright or inverted position as long as either the conventional entrance to the feed tube or the second opening is immersed in liquid. Hand pumps of this design function well. The only problems are that either the feed tube must have a slot cut in it or an additional adapter piece must be provided. Both requirements add to the cost of the unit.
It is seen that some of the prior art designs will function well only under some conditions and will increase the cost of the hand pump or spray valve assembly. Hand pump spray bottles and aerosol cans are produced at a rate of well over one billion units each year at a very low unit cost. Even a fraction of a cent increase to the manufacturing cost of the hand pump or aerosol can spray valve will result in a several percent increase in the total cost of the device. A small increase in cost to provide the invertibility will add millions of dollars to the total sales cost each year. As a result, it is important to produce the hand pump or aerosol can at a minimum unit cost that will operate reliably at any orientation at which the conventional feed tube opening or a secondary opening is covered with liquid.
There is a need for a hand pump or aerosol can spray valve assembly that can operate in the upright or inverted orientation, that embodies the conventional opening in the distal end of the feed tube and a single second opening at the opposite end of the feed tube, that does not require modification of the feed tube and that has no additional parts or moving parts.
Other needs that are satisfied by this invention will become apparent from the following detailed description of the invention and the accompanying drawings.